Cabo San Lucas, the Los Cabos area and all of Baja California Sur in Mexico is located in a time zone called Mountain Standard Time (GMT -7) same time zone as Denver, ie. one hour more than Pacific Standard Time. Read more on MST.
You can calculate the time by subtracting 7 hours from Greenwich Mean Time. As a reference use the time zone map below, MST is the greenish-colored area, you can expand it by clicking on it, if necessary.